Instead of combustion power generation,onshore power supply system gives an alternative electricity provision for cruise ship which is moored at the terminal.According to the development demands and trends of onshore power supply,this paper expounds functions and configuration characteristic of onshore power supply system,sums up the composition of shipshore side subsystems and the key technologies such as high-power static frequency converting,phase-locking,paralleling load transfer,cable tension detection,etc.This paper also provides different sorts of subsystem applications as reference to determine the entire proposal for Nansha cruise liner terminal,comes to a conclusion that high-high frequency converter with mobile cable system proposal is compatible.The advantages of this proposal are compactness,reliability and compatibility for connection.